This invention relates to an intake apparatus of a multi-cylinder internal combustion engine, and particularly to an intake apparatus of a multi-cylinder internal combustion engine having two inclined intake ports for every one cylinder in the cylinder head and which reduces the longitudinal length of the cylinder head.
In a multi-cylinder internal combustion engine, mounted on a vehicle, that arranges more than one cylinder in series, there is known an intake arrangement wherein two intake ports respectively cooperate with each cylinder and are arranged independently in a cylinder head, and cooperate with an intake manifold.
For example, as shown in FIG. 15 (prior art), cylinder head 102 is mounted on a cylinder block (not shown) of a multi-cylinder (for example, four cylinders consisting of first cylinder #1, second cylinder #2, third cylinder #3 and fourth cylinder #4) internal combustion engine, first to fourth fuel injectors 104-1 to 104-4 correspond to each cylinder. And, in manifold installing part 106 to which an intake manifold (not shown) is joined through a gasket (not shown), first low speed side port 108-1A and first high speed side port 108-1B functioning as first intake port 108-1 of first cylinder #1 are formed in the longitudinal direction of cylinder head 102 so that first fuel injector 104-1 is located in the center therebetween, and second low speed side port 108-2A and second high speed side port 108-2B as second intake port 108-2 of second cylinder #2 are formed in the longitudinal direction of cylinder head 102 so that second fuel injector 104-2 is located in the center. Similarly, third low speed side port 108-3A and third high speed side port 108-3B as third intake port 108-3 of third cylinder #3 are formed in the longitudinal direction of cylinder head 102 so that third fuel injector 104-3 is located in the center, and fourth low speed side port 108-4A and fourth high speed side port 108-4B as fourth intake port 108-4 of fourth cylinder #4 are formed in the longitudinal direction of cylinder head 102 so that fourth fuel injector 104-4 is located in the center. In addition, the first low speed side port 108-1A, the first high speed side port 108-1B, the second low speed side port 108-2A, the second high speed side port 108-2B, the third low speed side port 108-3A, the third high speed side port 108-3B, the fourth low speed side port 108-4A and the fourth high speed side port 108-4B are arranged on port centerline T1 which extends in the longitudinal direction (i.e., the crankshaft axis direction) of cylinder head 102.
In each first to fourth high speed side port 108-1B to 108-4B, first to fourth swirl control valve 110-1 to 110-4 are arranged, respectively. These first to fourth swirl control valve 110-1 to 110-4 are established with a valve constitution body (not shown) between intake port 108 and the intake manifold, that is, between the manifold installation part 106 of cylinder head 102 and an installation flange of the intake manifold, and is fixed to a valve axle 112 to be located on port centerline T1 and which penetrates each first to fourth low speed side port 108-1A to 108-4A, and is opened and closed by turning this valve axle 112. This valve axle 112 is operated by valve actuator 114.
In cylinder head 102, in order to support a delivery pipe (not shown) to distribute fuel to first to fourth fuel injector 104-1 to 104-4, first delivery pipe installing part 116-1, 116-1 corresponding to first cylinder #1, second delivery pipe installing part 116-2, 116-2 corresponding to second cylinder #2, third delivery pipe installing part 116-3, 116-3 corresponding to third cylinder #3, and fourth delivery pipe installing part 116-4, 116-4 corresponding to fourth cylinder #4 are arranged in a predetermined interval parallel to the longitudinal direction of cylinder head 102.
Examples of such intake apparatus of a multi-cylinder internal combustion engine are disclosed in published Japanese Patent Application Laid-Open Nos. 11-324835, 62-103448, 9-166025, and 8-246884. The intake apparatus of multi-cylinder internal combustion engine disclosed in published Japanese Patent Application Laid-Open No. 11-324835 supports an intake manifold on a cylinder head, and has a rubber gasket between intake manifolds as one set every two cylinders. The intake apparatus of multi-cylinder internal combustion engine disclosed in published Japanese Patent Application Laid-Open No. 62-103448, in the internal combustion engine establishes intake/exhaust valves consisting of three valves every one-cylinder, arranged so that path and hole established corresponding to a cylinder block are located to make a pair and have point symmetry with respect to the center of the cylinder head. The intake apparatus of multi-cylinder internal combustion engine disclosed in published Japanese Patent Application Laid-Open No. 9-166025 in a multi-cylinder internal combustion engine which possesses four valves every one-cylinder, arranges to incline an intake port to either end section of the cylinder head. The intake apparatus of multi-cylinder internal combustion engine disclosed in published Japanese Patent Application Laid-Open No. 8-246884 arranges a valve axle to fix each swirl control valve that arranges to a high-speed side port in an intake port of each cylinder, at the point that takes off from a position of each intake port.
And, in a traditional intake apparatus of a multi-cylinder internal combustion engine, as shown in FIG. 15, because an entrance end of each intake port (in a surface of manifold installing part that becomes an upstream side opening) is formed in the same shape for each cylinder and on the port centerline T1, and the intake port of the longitudinal end section side of the cylinder head extends a greater distance in the longitudinal direction. Accordingly, the prior art manifold installing part of the cylinder head is longer in the longitudinal direction of the cylinder head, resulting in a length L2. As a result, layout of the engine space of the vehicle is inconvenient, and placement of components becomes more difficult because of reduced space.
In addition, in FIG. 15, a valve axle for each swirl control valve is arranged to penetrate each low speed side port without a swirl control valve. Accordingly, there are inconveniences in that ventilation resistance in the low speed side port increases and output performance becomes worse.
To obviate or minimize the above inconvenience, the present invention provides an intake apparatus that comprises an intake port arrangement (e.g. 58-1) for a multi-cylinder internal combustion engine having two intake ports for each cylinder in a cylinder head of the internal combustion engine which has more than one cylinder in series and mounts an intake manifold to said cylinder, wherein said intake port arrangement (e.g. 58-1) has a low speed side port (e.g. 58-1A) and a high speed side port (e.g. 58-1B), and is arranged to incline each intake port located in the longitudinal end sections of the cylinder head as disposed on opposite sides of a transverse center plane.
In this invention, an intake port arrangement of a multi-cylinder internal combustion engine inclines each intake port as located in longitudinal end sections of the cylinder head, toward the transverse centerline of the cylinder head. Accordingly, a longitudinal length of an installing section of the cylinder head, on which an intake manifold is installed, can be shortened. As a result, the degree of freedom of layout of an internal combustion engine in an engine room is increased.